I rebuilt the kernel and copied bzImage to /boot/kernel-3.4.9-gentoo. Then I added the variables VIDEO_CARDS and INPUT_DEVICES to the /etc/portage/make.conf file as suggested.
By the way, I don't have that file in /etc/portage/. Shouldn't this be added to /etc/make.conf?

Anyway, I tried to emerge xorg-drivers but ran into some problems, because the USE variable wasn't set correctly (apparently I have to add python).

Nevertheless, without emerging xorg-drivers I rebooted my system. During the boot I'm getting some errors and the system crashes. Apparently, there is a kernel bug. I made a snapshot with my camera (see here). Nothing worked, so I had to reset the computer manually.
I booted with the liveCD removed the <*> Nouveau (nVidia) cards option and recompiled the kernel. Now everything is fine again, but I still don't what I did wrong.

Shouldn't this be added to /etc/make.conf? yes except /etc/portage/make.conf is ok also. apparently we are making a change for the sake of making a change just like redmond. Suggest your menuconfig look like: pick one of the red choices to match your motherboard chipset . No match = no choice.

I don't have advice offhand on the general problem, but in regards to this part:

steak-sandwich wrote:

Then I added the variables VIDEO_CARDS and INPUT_DEVICES to the /etc/portage/make.conf file as suggested.
By the way, I don't have that file in /etc/portage/. Shouldn't this be added to /etc/make.conf?

Both locations are valid, Portage will look for Both. However, /etc/portage/make.conf will override anything *also* in /etc/make.conf.
I installed 7 months ago? or thereabouts and the handbook used /etc/make.conf in examples but has since been modified.
I don't know if this is a migration process or if this was always the case and they decided it better for documentation to make
modifications to /etc/portage/make.conf since that would take precedence.

**Edit:
Since /etc is typically where you find configuration files on modern linux distros, it's possible they just felt it made more
sense to be in /etc/portage so it's clear the make.conf belongs to portage?